| 0950 | Perform mixture throughput test at MC = 77 K using above procedure with 3He pump on. Let G1 rise to ~500 mbar before Step 3, then it falls to ~50 mbar, then rises. Throughput = ~50 mbar/min (previously 25 mbar/min, but 2023 March measurement was 41 mbar/min, and 2021 measurement was 61 mbar/min). |
| 1000 | collecting mix back into dump. |
| 1000 | Preparing for LN blowout: https://zzz.physics.umn.edu/!cdms/cdms/k100/procedure/blow_out_ln2 |
| 1000 | Switch from turbo to LD. baseline level: 8e-8 |
| 1040 | Start blowing out LN. MB = 3 psi + atm. |
| 1040 | MC(Cernox) = 77.91 K. still = 71.3 K |
| 1110 | blowout finished. Only took 30 mins.. why?? LD rate 8e-8. MC(Cernox) = 77.94 K, still = 71.6 K |
| 1120 | Pumping out the MB using scroll. |
| 1140 | P2 is reading 0.1 mBar. Valve out scroll, p2 jumps to 0.8 mbar. Probably okay? Keep pumping. |
| 1140 | LD has been stable. Now at 5.5e-8. MC(Cernox) = 77.96 K, still = 71.8 K |
| 1140 | install Helium recovery bronze pipe (it had a leak and Mike (should have?) fixed it). |
| 1200 | Overpressurize MB to 2psi + atm. |
| 1240 | Add exchange gas to IVC. MXP (not to be trusted!) reads 180 mTorr = 239 uBar. |
| 1255 | Start LHe transfer. |
| 1255 | MC(Cernox) = 78.46 K; still = 72.5 K |
| 1305 | Put mix into the loop, but not circulating. |
| 1310 | MC(Cernox) = 65.43 K; still = 53.8 K, level meter =4%, MXP = 74 mTorr = 98 uBar, CC (Cold Cathode) = 5 mTorr = 6 uBar |
| 1320 | We trust the CC gauge more, which means we are short by a factor of 2 or 3. Added more exchange gas. |
| 1325 | MC(Cernox) = 52.63 K; still = 32.8 K, level meter =7%, MXP = 199 mTorr = 264 uBar, CC (Cold Cathode) = OL |
| 1330 | MC(Cernox) = 47.21 K; still = 24.0 K, level meter =20%, MXP = 168 mTorr = 223 uBar, CC (Cold Cathode) = OL |
| 1330 | Brought a helium cylinder as the one we've been using is running out. |
| 1335 | MC(Cernox) = 39.26 K; still = 20.3 K, level meter =32%, MXP = 153 mTorr = 204 uBar, CC (Cold Cathode) = OL |
| 1345 | MC(Cernox) = 28.81 K; still = 14.6 K, level meter =75%, MXP = 128 mTorr = 170 uBar, CC (Cold Cathode) = 10 mTorr = 13 uBar |
| 1355 | MC(Cernox) = 9 K, dropped directly from 17 K. Turn on turbo. level meter = 71%, the LHe tank is empty. stop He transfer. |
| 1410 | MC(Cernox) = 4.45 K, still = 6.0 K, level meter = 70%. |
| 1440 | Start pumping on 1K pot. 1K pot temperature dropped from 6 K to 3.1 K. |
| 1500 | Slowly opening up the needle valve. P2 is reading 5 mBar, 10 mBar, 15 mBar, 19 mBar, 30 mBar, 40 mBar. 1K pot final temperature 1.8 K. |
| 1520 | Start circulating mix with dump closed. slowly open V2 in steps: 1K pot pressure spike; G1 and G2 goes up too (kept under 650 mBar). |
| 1540 | Slowly open VT as well. did not notice significant jumps. |
| 1550 | Now injecting mix from the dump, slowly in steps. Keeping P1 and P2 between 400 mbar and 450 mbar. |
| 1600 | Use tower thermometer as an approximate for H35, which for some reason can not be read out. |
| 1600 | 1K pot temperature around 1.9 to 2.0 K. still = 2.6 K. MC(Tower) drops from 1.x K. |
| 1610 | MC(Tower) = 700 mK, still = 2.48 K, 1K pot = 1.9 K. |
| 1620 | MC(Tower) = 632 mK, still = 2.07 K, 1K pot = 1.97 K. liquid hitting the still? |
| 1635 | MC(Tower) = 250 mK, still = 2.00 K, 1K pot = 1.93 K. still temp doesn't drop?? |
| 1640 | MC(Tower) = 200 mK, still = 1.91 K, 1K pot = 1.94 K. |
| 1640 | Can we get to base???? |
| 1645 | MC(Tower) = 190 mK, still = 1.96 K, 1K pot = 1.96 K. |